Burner and method of burning fuel



- Se a, 1925.

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Patented Sept. 8, 1925.

UNITED STATES VERNON G. LEACH, OF CHICAGO, ILLINOIS.

BURNEE AND METHOD OF BURNING FUEL,

Application filed March 21, 1924, Serial No. 7oo,78e.

To all 'whom it may conccrm- Be it known that I, VERNON G. LEACH, acitizen of the United States, and a resident of the city of Chicago, inthe county of Cook and State of Il1inois,'have invented certain new anduseful Improvements, in .a Burner and Method of Burning Fuel; and I dohereby declare that the following is a full, clear, and exactdescription of the same, reference being had-to the accompanyingdrawings, and to the numerals of reference marked thereon, which form apart of this specification.

This invention' relates to a burner and method of burning fuel moreparticularly designed for pulverized fuel.

In the large majority of burners designed for the use of finely dividedfuel, the fuel is introduced into the furnace suspended in a current ofair, both air and fuel b Upon being introduced into the furnace, thefuel gives off its volatile content almost instantly, and this volatilecontent readily burns. The small particles' of devolatilized fuel,however, soon surround themselves with an atmosphere of carbon monoxideor carbon dioXide which has to( be scrubbed ofl' before furthercombustion can proceed. This scrubbing action is best brought about bythe Creation of a relative velocity between the fuel particle and thesurrounding atmosphere of gases. Either the fuel particles should travelfaster than the gases, or the gases should travel faster than the fuelparticles. If there is such relative 'movement of the particles and gas,the film of partially-consumed gases which surrounds each fuel particlewill be constantly scrubbed off and combustion will be completed in a Ishort length offiame travel.

Finely divided fuel, being highly explosive when thoroughly mixed andSuspended in the proper amount of air, should be introduced into thefurnace at a muzzle velocity that creates an ample margin of safety,between the velocity of the entering fuel and the velocity of rate offlame propagation, in order that the fire shall not creep back into the'feeder line and create an explosion. It is exceedingly difficult togive this desired muzzle velocity without drving the fuel a greatdistance through the fur-.

nace and creating a very long flame which', of course, wll necesstatevery large furnaces.

The principal object of the present inven- REISSUED tion it to providemeans and method for obtaining short fiame combustion and this isattained first by a high muzzle velocity. and second by instantlyspreading the entering air and fuel out over a wide area so that theirforward velocity is very greatly reduced, thus securing all the benefitsof a low velocity burner with the safety margin of the high velocityburner.

Now I have found that these advantageous results can be obtained by theuse of a burner having two passages therein adapted to project streamsof fuel and air obliquely inwards against each other to pro- "duce afan-shaped fiame in a plane perpendicular to the plane in which suchpassages lie.

The scrubbingaction, above referred to, is brought about by the rapidslowing up of the air introduced through the burner by the mutualimpingement of the jets which result in the spreading of the combustiblemixture in a fan-shaped spray'. The fuel particles have stored in them acertain amount of kinetic energy which causes thenr to shoot forward ata higher velocity than the air or gases in which they have beensupported.

Other and further important objects of this invention will be apparentfrom the disclosures in the specificati'on and drawings.

The invention (in a preferred form) is illustrated in the drawings andhereinafter more fully described.

On the drawings: v

Figure 1 is a side elevation of a burner constructed in accordance Withthe present invention.

Figur-e 2 is a plan'view of the same.

`Figure 3 is an end View of the same Figure 4: is a section on the line4,--4 of Figura 1.

' Figure 5 is a section on the line 5--5 of Figure 2.

Figure water tube type the improved burners.

Figure 7 -is a secton-'on the line 7- qf Figure 4.' v

Figura 8 is a vertical section through another form of 'watertube'.`boiler showing three alternative positions of the burner.

Figure 9 is a .vertical section through a Stirlng boiler' fitted withthe mproved burners.

6 is a vertical section through a boiler fitted witli one of&

Figure 10 is a section on theline 10--10 of Figure 7.

F igure 11 is a section through a reverbatory furnace fired by a burnerconstructed in accordance with the present invention.

As shown on the drawings:

The burner is constructed with two passages therein adapted to projectstreams of air carrying powdered fuel against each other to produce afan-shaped flame in a plane perpendicular to the plane in which saidpassages lie. Various forms of construction may beemployed. In theparticular form illustrated by way of example the burner 10 is formed'from a metal tube flattened at the end and depressed inwardly at itscenter portions as at 11, and provided with an exit orifice 12. Byflattening the tube and curving the ends inwardly two passages areformed on either side of the flattened portions 11 adapted to projectstreans of air and powdered fuel obliquely against each other. Theseimpinging streans create a fan-shaped flame perpenlicular to the planein which suclrpassages Je. i

Various installations of burners are shown in F igures 6 to 11inclusive. In Figures G and 7 a burner 14: is shown in connection with ahorizontally-baffled water-tube boiler comprising steam drum 15, header16, downcomer 17, tubes 18, brickwork setting 19 and battles 20 and 21.

The burner 14 is inserted through -an aper- -ture in the front wall ofthe boiler setting so as to direct a laterally extended sheet of flamebeneath the boiler.

In Figure 8' is shown three alternative applications of a burner 22 inconnection with a vertically baflled water-tube boiler.

An arrangement in which one, two or three burners maybe employedsimultaneously is shown in Figures 9 and 10 where burners 25, 26 and 27are employed for heating a Stirling or vertical water-tube type boiler.One of these burners 25 is arranged in the bottom of the combustionchamber While the other two, 26 and 27, are. located' at opposite pointsin the side walls of the combustion Chamber. i In Figure 11 a metalfurnace 30 is shown fitted with a burner 31 of the construction abovedescribed. Air is fed to the burner by means of a fan 32 andsimultaneously' powdered fuel is supplied to the burner from a bin 33 bythe feeder 34.

While a portion or all of the air required for combustion is introducedwith the fuel from a suitable blower, additional air may,

if desired, be introduced into the combustion chamber as for examplethrough apertures 28 as shown in Figures 6 to 10.

It is desirable that the fuel shall be intinatelyand uniformly mixed anddistributed throughout the current of air issuing from the burner. Inthe conveying and distribution of finely divided fuel Suspended in air,the tendency is for the particles of fuel to separate out and travelalong instrata or streaks, creating an uneven or spotted combustioncondition in the furnace. The construction of this burner is' such thatthe finely divided fuel is very intinately remixed or blended with theair in which it is Suspended at the very point of introduction into thefurnace. This nixing or blendingaction, coupled with the slow flamevelocity and acconpanied by the maximum difference in velocities betweenthe fuel particles and their surrounding atmosphere causes the flame tobe unusually short and the combustion efficieney to be very high. Tothese advantages may be added the margin of safety created by a highmuzzle velocity which is ordinarily much higher than the rate of .flamepropagation.

I ani aware that many changes may be made and numerous detals ofConstruction i may be Varied through a wide range without departing fromthe principles of this invention, and I-there'fore do not purposelmiting the patent granted otherwise than necessitated by the prior art.

I claim as my invention:

1.An apparatus for burning powdered fuel comprising a source ofpowdered-fuel, a source of air under sufiicient pressure to project thepowdered fuel mixed therewith through a burner at a speed greater thanthe speed of flame propagation through the mixture, said burner havingtwo passages therein adapted to project streans of air carrying powderedfuel obliquely inwards against each other to produce a fan-shaped flamein a plane perpendicular to the plane in which said passages lie.

2. A method of burning powdered fuel conprising projecting two streamsof air carrying powdered fuel against each other at a speed greater thanthe speed of flame propagation whereby ignition does not occur until thevelocity of the streans is reduced by the mutual impingement.

In' testimony whereof I have hereunto

